In recent years, circuit boards and other electronic parts used in the field of touch panels, solar batteries and capacitors have been required not only to be made thinner and lighter, or be made lower in load onto the environment, but also to be exhaustively improved in yield to be improved in price competitive power.
A method of forming a conductive pattern over a circuit board is known, specifically, a conductive pattern producing method of coating a paste in which conductive particles are dispersed in a resin, drying the paste, exposing the resultant workpiece to light, developing the workpiece to form a fine pattern, and heating the workpiece to shrink the formed pattern to bring the conductive particles into contact with each other, thereby causing the pattern to express conductivity (see Publication originating from Japanese Patent Application No. 04-327423, Publication originating from Japanese Patent Application No. 2009-286095, and Publication originating from Japanese Patent Application No. 2009-276102).
However, in the conventional conductive pattern producing method, the heating treatment to bring the conductive particles into contact with each other to cause the pattern to express conductivity needs to be conducted at high temperature over a long period. When this treatment is applied to actual production, production efficiency thereof is remarkably low. Moreover, the high-temperature and long-period heating treatment may probably deteriorate the substrate or other members. In the existing circumstances, therefore, it has been required to develop a production method of yielding a fine conductive pattern while these problems are avoided.
Thus, it could be helpful to provide a conductive pattern producing method capable of yielding a conductive pattern good in conductivity, and improving the production efficiency thereof remarkably by use of light rays having a broad spectrum without conducting any heating treatment at high temperature over a long period.